Rheumatoid arthritis (RA), an autoimmune disease, causes inflammation of the joints, leading to pain and degeneration over time. Further research on RA has also shown links to neurological factors, including depression and cognitive impairment, which need to be investigated further. A recent research study from the Institute of Basic Science investigated the ability of a treatment to target both inflammatory and neurological factors.
For this study, the authors focused on monoamine oxidase (MAO-B), an enzyme involved in removing neurotransmitters (chemical signals) in the brain such as dopamine and serotonin. Currently, RA treatments involve the use of monoamine oxidase inhibitors as a way to reduce joint inflammation and pain. The authors revealed that one of the key molecules in causing RA inflammation, interleukin-1𝛽, interrupts the normal expression patterns of MAO-B in joint tissues from RA patients. The abnormal MAO-B expression leads to the production of more inflammatory molecules, which can make symptoms worse.
The authors further looked at cognitive function using an RA mouse model to conduct a series of behavior assays. From this, the authors observed that the RA mice had higher levels of cognitive impairment and were unable to recognize objects or locations after the previous introduction. Further investigation of brain tissue found abnormal MAO-B expression in the hippocampus, a center in the brain involved in memory formation. Certain cells in the brain called astrocytes are very sensitive to damage and inflammation. Astrocyte response to damage results in forming of scar tissue, which impairs the function of brain tissue, leading to cognitive impairment.
This novel study has established a mechanism by which RA inflammation can lead to cognitive impairment that can worsen over time. The authors have continued to expand on their findings by using a newly developed selective MAO-B inhibitor, which was able to improve both inflammation and cognitive function in mice. This treatment is also currently being tested in a clinical trial in humans, so it could lead to a revolutionary treatment that could potentially improve the quality of life for RA patients.
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